1. Field of the Invention
The present invention is directed to a process for producing rewettable mats, staple fibers, and articles such as battery separators from nonwoven mats of polyolefin fibers. More specifically, the present invention relates to the sulfo-chlorination of a nonwoven mat of polyolefin fibers and preferably the treatment thereof with an amine followed by recovery of individual fibers or compaction so that the compacted mat forms a useful structure such as one suitable as a battery separator which is rewettable, or one suitable as an adsorbtive liner for diapers.
2. Prior Art
The Journal of Applied Polymer Science, Vol. 16 (1972) at pp. 535-538, contains an article relating to chloro-sulfonation of polyethylene film. Furthermore, it is too late in time to be available as a reference, and also is not relevant, because it is directed to films, which require a different type of treatment.
Belgium Pat. No. 788,672, issued 2/1/73, discloses the use of high chloro-sulfonation levels for making staple fibers water dispersable. In addition, it is too late in time to be available as a reference for mats.
British Pat. No. 952,111 is directed to producing a chemically active solid polyolefin surface, e.g., films, to which adhesives, dyes, inks and coatings in general will adhere, and which have little tendency to pick up static charge. The procedure described comprises exposing the polyolefin surface to a mixture of gaseous sulfur dioxide and chlorine in the presence of ultraviolet light to thereby form very small quantities of sulfochloride groups and reacting these sulfochloride groups at the surface of the polymer with a reagent selected from the class consisting of ammonia, monomines, polyamines, monohydric alcohols, polyhydric alcohols, alkylene oxides and aqueous alkali metal hydroxides.
The melt-blown processes used to make the porous non-woven mats which are then treated according to the invention are described in several issued patents such as Prentice, U.S. Pat. Nos. 3,704,198 and 3,650,866, which are incorporated herein by reference.